Mill roll changing arrangement

ABSTRACT

A quick-replaceable roll assembly for a rolling mill stand, said assembly comprising an inner carriage, rail engaging wheels rotatably mounted on said carriage, means for mounting a lower roll and a pair of bearing structures therefor on said carriage, said means comprising a number of balancing plungers reciprocatably mounted on said carriage and engaging said bearing structures, and means for mounting an upper roll and bearing structures therefor on said assembly in faced engagement with said lower roll.

United States Patent Hlafcsak [451 Sept. 19, 1972 [54] MILL ROLL CHANGING 3,367,162 2/1968 Kazebee et al ..72/237 X ARRANGEMENT [72] Inventor: Joseph L. Hlafcsak, Pittsburgh, Pa. imary s fg fi orneyon 1111 [73] Assrgnee: Mesta Machine Company, Pitt- Sbursh, 57 ABSTRACT [22] Filed: 3,1971 A quick-replaceable roll assembly for a rolling mill [211 App] 112,336 stand, said assembly comprising an inner carriage, rail engaging wheels rotatably mounted on said carriage, means for mounting a lower roll and a pair of bearing 8 g structures therefor on said carriage, said means com- [g l l prising a number of balancing plungers reciprocatably mounted on said carriage and engaging said bearing structures, and means for mounting an upper roll and [56] References cued bearing structures therefor on said assembly in faced UNITED STATES PATENTS engagement with said lower roll.

3,330,142 7/1967 Thompson ..72/8 9 Claims, 7 Drawing Figures PATENTED SEP 1 9 m2 SHEET 2 0F 4 PATENTEDSEP 19 I972 sum 3 or 4 wNN MILL ROLL CHANGINGARRANGEMENT The present invention relates to a rolling mill and more particularly to a roll changing rig or similar means to facilitate replacing the work rolls of the one or more mill stands of the mill. The invention is especially useful in conjunction with wide flange and other structural mills wherein product changes are frequently made, which of course necessitate corresponding work roll changes in addition to replacement of worn out work rolls.

Although the invention is described primarily in conjunction with structural mills and more particularly a wide flange beam mill, it will be observed that the principles of the invention can be applied to advantage to other types of mills such as plate, strip, or slabbing mills.

As intimated above, the operation of most beam and other structural mills requires frequent product changes and attendant replacement of the work rolls to accommodate the several products of a typical structural mill. In many cases it is necessary to change the mill rolls as frequently as eighty to ninety times per month. Of course the number of changes will vary from one installation to the next and the numbers of these changes, moreover, are dictated primarily by product changes rather than by replacement of worn work rolls. In most structural mills, the work rolls exhibit ailong wearing characteristic, as the rolling forces are usually about half of those encountered in a typical cold mill. However, the tolerances of the work rolls in most structural mills are more critical, e. g. to ensure orthogonality of flanges in the case of a beam mill and in general the straightness of the structural members. These considerations contribute to the frequency of and necessity of roll changes in a typical structural mill, including but not limited to a wide flange beam mill of either the dual or single purpose variety. It is impossible to minimize the importance of shortening the mill down time by decreasing the time and labor involved in the aforementioned relatively large number of roll changes.

Known forms of mill roll changing procedures for this purpose have consumed inordinant amounts of time and labor for withdrawing the mill rolls from each mill stand and replacing them with a new set of rolls either for product changes or for wear consideration. In consequence, production programs have been unduly lengthened and unit production time has been unavoidedly increased, particularly for short-run products. Known procedures also have resulted in the use of additional operating personnel, who are not otherwise necessary to the actual operation of the mill.

In addition to the physical difficulties involved in handling and transporting the replacement mill roll, known roll changing procedures have dictated a rather extensive adjustment or zeroing program after the installation of the replacement rolls and in preparation for a change in products or in product dimensions. Conventionally, after installation of the replacement rolls it is necessary to establish a predetermined reference point with respect to the mill stand and the newly replaced rolls. In the case of a beam mill both the horizontal and vertical roll assemblies must the be adjusted after the replacement procedure with respect to the reference point. After the material to be rolled has entered the work roll area subsequent adjustment is required owing to plastic deformation of the work rolls and the like, is likewise minimized or eliminated altogether at thg rolling mill site. In particular the roll change rig is arranged such that assembly and disassembly of the work rolls can take place in the roll shop or other location remote from the mill stand. Insofar as operation of the rolling mill itself is concerned, the mill rolls can be withdrawn and quickly replaced as a unit or complete assembly all of which contribute to a pronounced and unexpeEt'tT minimization of the mill down time, in contrast to known roll changing procedures. Naturally, the productional losses intended upon known procedures of roll change are likewise minimized or largely eliminated.

Of prime importance, and potentially of even greater importance is another unexpected feature of my invention. This is the capability of the replacement roll assembly to be zeropositioned as a unit outside of the mill stand. Both the horizontal and vertical rolls (in case of a beam mill) can be adjusted to a definite or predetermined reference point, as required..The significant and unobvious character of this feature of the invention is readily apparent from the fact that the replacement roll assembly can be zero-positioned in the roll shop either during or before withdrawal of the previous roll assembly from the mill stand. With the capability of zero-positioning the replacement roll assembly externally of the mill stand, the mill obviously can be readied for production within a much shorter interval of down time.

Inside the mill stand, the replacement roll assembly can be lowered quickly onto a number of stops permanently mounted in the mill housing in further reduction of replacement time. When the replacement assembly is thus inserted and seated in the mill housing, the bottom mill screw-ups can be actuated to raise the bottom roll of the assembly into operating position, and the top roll screw-downs as well as the vertical roll screws can be quickly and efficiently actuated to their new operating positions.

I accomplish these desirable results by providing a quick-replaceable roll assembly for a rolling mill stand, said assembly comprising an inner carriage, rail engaging wheels rotatably mounted on said carriage, means for mounting a lower roll and a pair of bearing structures therefor on said carriage, said means comprising a number of balancing plungers reciprocatably mounted on said carriage and engaging said bearing structures, and means for mounting an upper roll and bearing structures therefor on said assembly in faced engagement with said lower roll.

I also desirably provide a similar roll assembly wherein said carriage includes a pair of shelf structures for mounting said vertical roll structures respectively.

muuA a: 12

4 such that each of said auxiliary track sections can be selectively inserted into said external track section at said interruption to bridge said interruption, said platform and either of said auxiliary track sections being capable of supporting said roll assembly at position such thatanother of said roll assemblies can be transversed along said external'track section and the other of said auxiliary track sections without interference from the first-mentioned roll assembly.

I also desirably provide a similar roll assembly including said mill stand having a stationary housing and a movable housing, and means for mounting said mova ble housing for movement longitudinally of said elevatable rails to accommodate differing lengths of roll assemblies within said mill stand.

In the method aspect of my invention I desirably'provide a method for setting roll openings in a roll assembly having upper and lower horizontal rolls and a pair of vertical rolls juxtaposed thereto, said method comprising the steps of aligning said vertical rolls relative to a common vertical roll pass line, elevating said lower horizontal roll to face on said pass line, elevating said. upper horizontal roll to face against said lower horizontal roll at said pass line to establish a zero roll position, and applying preloading forces to said roll assembly within said mill stand sufficient to induce substantially maximum roll deformations in said assembly and associated components and in said mill stand in order to establish a reference roll position.

I also desirably provide a similar method including the additional steps of relieving said preloading force and withdrawing said rolls from one another to establish roll gaps correspondingly less than the rolling dimensions, and inserting a work piece among said rolls to expand said rolls precisely to said rolling dimensions.

During the foregoing discussion, various objects, features and advantages of the invention have been set forth. These and other objects, features and advantages of the invention together with structural details thereof will be elaborated upon during the forthcoming description of certain presently preferred embodiments of the invention and presently preferred methods of practicing the same.

In the accompanying drawings, I have shown certain presently preferred embodiments of the invention and have illustrated certain presently preferred methods of practicing the same, wherein:

FIGS. '1 and 1A constitute a composite tope plan view, partially in section, of one form of rolling mill stand together with a roll changing arrangement therefor.

FIG. 2 is a side elevational view, partially in section, of the equipment shown in FIG. 2.

FIG. 3 is a front elevational view of the mill mill stand shown in FIG. 1, partially sectioned, and taken generally along reference line 3-3 thereof and FIG. 4 is a side elevational view of the roll change rig shown in FIG. 1 and taken along reference line 4-4 thereof FIG. 6 is a front elevational view of the apparatus as I shown in FIG. 5, with parts insection and other parts broken away to illustrate the invention more clearly.

Referring now more particularly to FIGS. 1-4 of the drawings, the exemplary form of the invention shown therein comprises a mill stand 10 and a roll changing rig denoted generally by the reference character 12. The mill stand 10 in this example includes a pair of housings 14, 16 with the housing 16 being mounted for movement along a pair of rails 18 The moveable housing 16 thus can be moved to a position relative to the stationaryhousing 14 as to accommodate a particular length of roll assembly 20 therein. The two housings 14, 16 are stabilized by pairs of rods 17, 19 which are rigidly secured to one of the housings for example the stationary housing 14 and are engaged with the other of the housings by slideable insertion through aperture means 21. Generally the housings 14, 16 are'aligned with upper and lower bearing chocks of the roll assembly 20 when in their operating positions. In the particular example shown the roll assembly 20 is of minimum length, with the result that the upper and lower sections of the housings 14, 16 can be placed in abutting relation as evident from FIG. 2. As also shown in the latter figure the roll assembly 20 is mounted on an inner carriage 26 provided with a set of rail engaging wheels 28. The wheels 28 are so spaced and are otherwise shaped to engage elevatable rail sections 30 of the mill stand 10, intermediate section 36a, auxiliary rail sections 32 of the side shifting car 34, and the external section 36b.

In the disclosed arrangement of the invention, the roll assembly 20 is shaped for closely fitted insertion through a window 38 of each of the mill stand housings 14, 16, as better shown in FIG. 3. The roll assembly 20 in this case is configured for rolling wide flange beams and the like and includes upper and lower horizontal rolls 40, 42 and vertical rolls 44, 46, all of which are mounted, as presently described on the inner carriage 26 to form with the carriage 26 the unitary roll assembly 20. In furtherance of this purpose, the upper horizontal roll bearing chocks 48, 50 are nested onto the vertical roll housings 52, 54 respectively, each of which are troughed at 56 for this purpose. Each'of the vertical roll housings 52, 54 is provided with spacers 58 to aid in aligning the upper horizontal roll chocks 48, 50. Each of the vertical roll housings S2, 54 in turn is slidably mounted respectively on shelf structure 53 or 55 of the inner carriage 26 in contrast to previous practices of mounting the vertical rolls directly on the mill housings. Each lower horizontal roll bearingchock 60 or 62 is provided with means such as the spacers 64 for aligning the vertical rolls 44, 46. In furtherance of this purpose each vertical roll housing 52, 54 is provided with a pair of downward extensions 66 each of which is notched at 68 for engagement with positioning plungets 70 which are mounted in the inner carriage 26 as shown. The plungers 70 and extensions 66 therefor stabilize and position the vertical roll housings 52, 54 on the roll assembly 20 and particularly with respect to the upper and lower rolls 40, 42.

Similarily the inner carriage 26 is provided with pairs of plungers 72 for similarily elevating and balancing the lower horizontal roll 42. The plungers 72 can be hydraulically actuated if desired, and the plungers can be fitted into suitable bores or cylinders for that purpose.

Roll necks 74, 76 of the upper and lower horizontal rolls 40, 42 respectively protrude through the associated bearing chocks for engagement by suitable drive spindle couplings (not shown). The vertical rolls 44, 46 are not necessarily driven in this application.

The inner side of the inner carriage 26 is provided with a number of stop surfaces 78 at which the inner carriage is brought to rest on pairs of stops 80 permanently secured to the sill structure 82 of each housing window 38 as better shown in FIG. 3. The stop surfaces 78 and stops 80 are engaged when the mill stand rail sections 30 are lowered, for example by actuation of cylinder arrangements 84. At this time the roll assembly including the inner carriage 26 is stationarily and rigidly supported on the pairs of housing stops 80. However, before operation of the mill stand is commenced, it is in accord with another unexpected feature of my invention that the inner carriage 26 is completely unloaded as far as the roll assembly 20 is concerned, and the lower roll 42 of the latter is supported directly by the mill housings 14,16. This accomplished by supporting the roll assembly, in particular the lower horizontal roll 42 thereof, directly by the mill stand screw-ups 86.

In furtherance of this purpose each screw-up 86 is threaded through the bottom of each mill housing 14 or 16 and extends into bearing engagement with the associated lower horizontal roll chock 60 or 62 through an aperture 88 therefor in the adjacent end of the inner carriage 26 (FIGS. 2 and 3). Thus, when the roll assembly 20 has been properly installed within the mill housings l4, 16 by convenient use of the inner carriage 26, the roll assembly 20 then can be engaged directly by the mill stand in the usual manner. For this purpose each vertical roll housing 52 or 54 is provided with a pair of inclined stop surfaces 90 for engagement respectively by a pair of clamping plungers 92 carried in the associated mill housings 14 or 16.

The position of inner carriage 26 within the mill stand is secured by a pair of lower clamp plates 94 mounted on the moveable housing 16 adjacent the window 38 thereof to properly contain the roll assembly 20 in the mill stand 10. Similar and cooperating upper clamp plates 96 can be mounted in like manner on the moveable housing 16 adjacent the window 38 for the same purpose.

The upper horizontal roll 40 can be positioned for adjusting the horizontal roll gap by means of screwdowns 100 mounted in the upper sections of the mill housings 14, 16. Likewise, hold-down forces also are applied to the work roll chocks 48, 50 of the upper horizontal roll 40 by means of the same screwdowns 100..

As noted previously the elevatable housing rails 30 are aligned with the intermediate track section 36a which is interrupted at 37, and with the juxtaposed pair of the auxiliary track segments 32a or 32b of the side shifting car 34 depending on the position thereof, and with the external track section 36b. The external track section 36b can extend to a roll shop (not shown) or to suitable warehousing facilities for the roll assemblies located remotely of the rolling mill.

The use of the side shifting car 34 affords a temporary holding area for a replacement roll assembly 20a to permit withdrawal of the used roll assembly 20 (FIG. 1) without interference between the withdrawn and replacement roll assemblies.

The side shifting car 34 provided in accordance with this feature of the invention, includes a platform 102 supported on axles 104 and railway trucks 106. The car 34 is moveable along a relatively short length of track including rails 108. Mounted on the platform 102 are the pairs of rails 32a, 32b mentioned previously. These rails are spaced sufficiently to permit passage of the roll assemblies 20, 20a or other forms of roll assemblies, the widths of which are limited by the housing windows 38. The width of the car platform 102 provides rail segments 32a, 32b of sufficient length to accommodate the longest roll assembly that can be incorporated into the side shifting mill housing structure 14, 16. An example of such roll structure is denoted at 20b in FIGS. 5 and 6 of the drawings. FIGS. 5 and 6 also show the rods 17, 19 in the expanded position and the increased separation of the mill stand housings l4, 16 to incorporate the longer roll assemblies 20b.

The platform 102, including the rails 32a, 32b which can be recessed therein as shown in FIG. 4, is mounted on a base structure 103 for added strength, which in turn is mobilized by the axles 104 and railway trucks 106.

As better shown in FIGS. 1 and 4, slideable metal plates 110, 112 can be joined respectively to the end portions of the car platform 102 to cover the well 114 or recess in which the side shifting car 34 is reciprocated. The sliding plates 110, 112 thus provide coverage for the car well 114 irrespective of the position of the side shifting car 34. A personnel hazard is thereby eliminated.

The carrying out of the roll-changing procedure will now be described. Prior to withdrawal of the used roll assembly 20 (FIG. 1), replacement roll assembly 20a is brought from the roll shop or from a suitable storage area along the external track section 36b. Suitable traction means (not shown) can be employed to propel the replacement roll assembly 20a along the external track section 36b. Before the replacement roll assembly 20a reaches the side shifting car 34, the latter is reciprocated to the left of its position as shown in FIG. 1, such that its auxiliary track section rail segments 32b are aligned with the external track section 36b. The replacement roll assembly 20a is then pushed onto the side shifting car 34 and the latter is moved to the right to the position thereof as shown in FIG. 1. This places the replacement roll assembly 20a in the position as shown in FIG. 1 so that the used roll assembly 20 when withdrawn, can be wheeled directly to the roll shop or other location by means of the elevatable mill rails 30, the intermediate track section 360, the side shifting car rail segments 32a, the external track section 36b, all of which are then aligned therewith as illustrated in FIG. 1. One of the unexpected results of the invention, in addition to the use of the side shifting car 34, is that separate carriage means do not have to be supplied for each of the roll assemblies 20, 20a, as this function is,

provided by the inner carriage 26 which forms part of each roll assembly 20 or 20a in accordance with the invention.

Owing to the unitary character of the roll assembly or 20a or equivalent assembly made in accordance with the invention, the roll assembly can be leveled and zeroed externally of the mill stand 10. This can be accomplished either in the roll shop or on the side shifting car 34 when the replacement roll 20a is located thereon as shown (FIG. 1). The obvious advantage of this feature of this invention is the accomplishment of such leveling and/or zeroing or other adjustment of the replacement roll assembly 20a prior to shutting down the rolling mill including the mill stand 10, with the admirable result that mill down time is drastically reduced.

In the case of the wide flange beam roll assembly 20a a typical roll leveling and zeroing procedure in accordance with the invention will now be described, as it falls into the general category of mill roll replacement procedure. Initially suitable hydraulic lines (not shown) or other source of motive power are coupled to the replacement roll assembly 20a in order to actuate the various hydraulic plungers described previously. The lower horizontal roll 42 is then raised by means of plungers 72 to the normal pass line (not shown) of the mill stand 10, with the assumption that the replacement roll assembly 20a is supported externally at the same elevation as is maintained in the mill stand 10, irrespective of whether the assembly is supported on the side shifting car 34 or on the external track section 36b at the roll shop. At this position the lower roll 42 is faced against the upper horizontal roll 40. The vertical roll housings 52, 54 are now moved toward the horizontal rolls 40, 42 by means ofplungers 70 until the vertical rolls 44, 46 just touch the sides of both horizontal rolls for vertical alignment of the horizontal rolls. The venical roll housings are consequently aligned by means of spacers 64 positioned in the lower horizontal roll chocks 60, 62 such that the center lines of the vertical rolls 44, 46 are aligned with the interface 41 of the engaged upper and lower horizontal rolls 40, 42 at a predetermined material pass line 116. The upper horizontal roll 40 likewise can be aligned as necessary by means of spacers 58 positioned in the vertical roll housings.

The horizontal and vertical rolls 40-46 are now zeroed with one another and the replacement roll assembly 20a is ready for traversing into the mill stand 10. The aforedescribed zeroing is preserved owing to the unitary character of the mill roll assemblies, as described previously.

After the replacement roll assembly 20a is thus readied for insertion into the mill stand 10, the mill is then shut down preparatory to withdrawing the used roll assembly 20.- The upper horizontal roll balance (bracket 98) is deactivated to permit the upper horizontal roll 40 again to face and rest on the lower horizontal roll 42. The vertical roll screws 24 are then retracted to their outward limits. The carriage assembly clamp plates 94 and the upper horizontal roll clamp plates 96 are opened in order to permit the roll assembly 20 to be raised to its roll change position by raising the mill stand rails by cylinders 84 to a position of alignment with the intermediate track section 360. The bottom screw-ups 86 are then retracted to clear the inner roll assembly carriage 26.

After raising the spindle carriers (not shown) to support the drive spindles (not shown) which are withdrawn from the horizontal roll necks 74, 76 on the drive side, the used roll assembly 20 is withdrawn through the mill stand windows 38 by suitable traction means (not shown) across the mill rails 30, the intermediate track section 36a and onto the side shifting car 34.

The side shifting car 34 is then actuated by suitable traction means (not shown) to the position thereof as shown in FIG. 1 to remove the used roll assembly 20 from its position in front of the mill stand 10 to the position denoted by replacement roll assembly 20a of FIG. 1. The used roll assembly'20 is now removed from in front of the mill stand 10 preparatory to insertion of the replacement roll assembly 200 into the mill along the intermediate track section 360.

As an initial step in the re-insertion procedure, the drive spindles (not shown) are adjusted radially, if required, to receive the replacement rollassembly 20a. At the same time the drive spindles are raised to receive the roll necks 74, 76 of the replacement roll assembly 20a. The replacement roll assembly 20a including its inner carriage 26 is then traversed intothe mill stand 10 where it is positioned within housing windows 38. The clamp plates 94 and 96 are closed, thus properly containing the replacement roll assembly 200 within the mill stand. The spindle carriers are then retracted, whereupon the elevatable mill stand rails 30 are lowered to permit the replacement roll assembly 20a to rest on the mill housing stops 80. The housing screw-downs 100 are then lowered to engage the upper horizontal roll chocks 48, 50, after which the screwdowns 100 are leveled for proper alignment of the replacement roll assembly 20a. The bottom screw-ups 86 at this time are raised for insertion through the inner carriage 26 into engagement with the lower horizontal roll chocks 60, 62 respectively. After leveling the screw-ups 86, the bottom lift cylinders or plungers 72 of the inner carriage 26 are retracted from the lower roll chocks 60, 62. The vertical roll screws 24 of each mill housing 14 or 16 are run in to touch the vertical roll housings 52, 54 and then leveled. The vertical roll positioning cylinders or plungers are deactivated followed by energization of the vertical roll balance cylinders. The upper horizontal roll balance bracket 98 is then engaged to complete the installation procedure.

Prior to insertion into the mill stand, the replacement roll assembly 20a can be prepared in the roll shop. The inner carriage 26 is placed on the external track section 36b. The thickness of the spacers 64 is established in proportion to the roll radius of the lower horizontal roll 42 in order to face the roll on a pass line of the roll assembly 20a which can thereafter be aligned to coincide with the material pass line 116 of the mill stand. The verticalroll assemblies including their housings 52, 54 are then added to the roll assembly 20a as shown in FIGS. 2 and 4, with the vertical roll housings engaging the spacers 64 and the vertical, roll adjusting cylinders 70. The upper horizontal roll spacers 58 are likewise adjusted in proportion to the roll radius of the upper horizontal roll 40 such that the roll is faced approximately against the lower horizontal roll 42 at the material pass line 116. The roll assembly is then transferred to the side shifting car 34 as outlined above.

After the replacement r'oll assembly a is zeroed as described above externally of the mill stands 14, 16 the assembly is inserted into the mill stand through the housing windows 38. With all the rolls at the zero position, and with the roll assembly aligned such that its pass-line coincides with a predetermined material pass line 1 16 of the mill stand, the entire roll assembly 20a is preloaded within the mill stand by means of the horizontal and vertical screws to establish a positive reference at the zero position. This is made possible by applying sufficient preloading forces to subject the roll assembly to the anticipated elastic deformations encountered during the rolling operation. The preload force therefore should be at least equal to the maximum anticipated rolling force. The preload forces are then relieved and the mill controls are operated to back off the vertical and horizontal rolls to openings therebetween which are less than the rolling dimensions by predetermined values. The roll openings then are expanded to the precise rolling dimensions by insertion of a work piece.

From the foregoing it will be apparent that novel and efficient forms of Mill Roll Changing Arrangement have been described herein. While I have shown and described certain presently preferred embodiments of the invention and have illustrated presently preferred methods of practicing the same it is to be distinctly understood that the invention is not limited thereto but may be otherwise variously embodied and practiced within the spirit and scope of the invention.

lclaim:

1. A method for setting rollopenings in a roll assembly for a mill stand, said assembly having upper and lower horizontal rolls and a pair of vertical rolls juxtaposed thereto, said method comprising the steps of aligning said vertical rolls with a roll assembly pass line, elevating one of said horizontal rolls to face on said pass line, elevating the other of said horizontal rolls to face against said one horizontal roll at said pass line to establish a zero roll position, and thereafter applying preloading forces to said roll assembly within said mill stand sufficient to induce substantially maximum deformations in said assembly and associated components and in said mill stand in order to establish a reference roll position.

2. The method according to claim 1 including the additional steps of relieving said preloading forces and withdrawing said rolls from one another to establish roll gaps correspondingly less then predetermined rolling dimensions, and inserting a work piece among said rolls to expand said rolls precisely to said rolling dimensions.

3. The method according to claim 1 wherein said preloading forces are at least equal to maximum anticipated rolling forces.

4. The method according to claim 1 including the modified steps of performing said aligning and elevating steps prior to inserting said roll assembly into said mill.

5. The method according to claim 1 including the additional step of coinciding said roll assembly pass-line with a predetermined material. pass-line of said mill stand prior to application of said preloading forces.

6. The method according to claim 1 wherein motive means are provided on said roll assembly for elevating said horizontal rolls and for aligning S31 vertical rolls,

and said elevating and lining steps are accomplished by actuation of said motive means respectively.

7. A method for setting roll openings in a roll assembly for a mill stand, said assembly having a pair of lower horizontal rolls and a pair of vertical rolls juxtaposed thereto, said method comprising the steps performed on said roll assembly outside of said mill stand of aligning said vertical rolls with a roll assembly passline, elevating one of said horizontal rolls to face on said pass-line, elevating the other of said horizontal rolls to face against said one horizontal roll at said passline, and bringing each of said vertical rolls into engagement with both of said horizontal rolls to establish a zero roll position.

8. The method according to claim 7 including the additional steps of inserting said roll assembly into said mill stand, and coinciding the pass-line of said roll assembly with a predetermined material pass-line of said mill stand.

9. The method according to claim 8 including the additional step of preloading said roll assembly within said mill stand to establish a reference roll position. 

1. A method for setting roll openings in a roll assembly for a mill stand, said assembly having upper and lower horizontal rolls and a pair of vertical rolls juxtaposed thereto, said method comprising the steps of aligning said vertical rolls with a roll assembly pass line, elevating one of said horizontal rolls to face on said pass line, elevating the other of said horizontal rolls to face against said one horizontal roll at said pass line to establish a zero roll position, and thereafter applying preloading forces to said roll assembly within said mill stand sufficient to induce substantially maximum deformations in said assembly and associated components and in said mill stand in order to establish a reference roll position.
 2. The method according to claim 1 including the additional steps of relieving said preloading forces and withdrawing said rolls from one another to establish roll gaps correspondingly less then predetermined rolling dimensions, and inserting a work piece among said rolls to expand said rolls precisely to said rolling dimensions.
 3. The method according to claim 1 wherein said preloading forces are at least equal to maximum anticipated rolling forces.
 4. The method according to claim 1 including the modified steps of performing said aligning and elevating steps prior to inserting said roll assembly into said mill.
 5. The method according to claim 1 including the additional step of coinciding said roll assembly pass-line with a predetermined material pass-line of said mill stand prior to application of said preloading forces.
 6. The method according to claim 1 wherein motive means are provided on said roll assembly for elevating said horizontal rolls and for aligning said vertical rolls, and said elevating and lining steps are accomplished by actuation of said motive means respectively.
 7. A method for setting roLl openings in a roll assembly for a mill stand, said assembly having a pair of lower horizontal rolls and a pair of vertical rolls juxtaposed thereto, said method comprising the steps performed on said roll assembly outside of said mill stand of aligning said vertical rolls with a roll assembly pass-line, elevating one of said horizontal rolls to face on said pass-line, elevating the other of said horizontal rolls to face against said one horizontal roll at said pass-line, and bringing each of said vertical rolls into engagement with both of said horizontal rolls to establish a zero roll position.
 8. The method according to claim 7 including the additional steps of inserting said roll assembly into said mill stand, and coinciding the pass-line of said roll assembly with a predetermined material pass-line of said mill stand.
 9. The method according to claim 8 including the additional step of preloading said roll assembly within said mill stand to establish a reference roll position. 